Modification of corn straw to control carbon release: Enhancing its utilization value as a carbon source of constructed wetland

Corn straw has attracted significant attention for high-value biomass utilization. Modified corn straw has potential as a sustainable solid carbon source for constructed wetland (CW) applications. This study examined unaged and aged corn straw as biomass materials and analyzed the changes in electrical conductivity (EC), chemical oxygen demand (COD), and dissolved organic carbon (DOC) under different modification conditions to determine suitable conditions for stable carbon release. The results showed that KMnO 4 (0.05 mol·L −1 ) modified unaged corn straw exhibited continuous and substantial organic matter release. Aging improved the long-term stability of modified corn straw. KMnO 4 (0.05 mol·L −1 ) and KMnO 4 (0.05 mol·L −1 ) + HCl (0.004 mol·L −1 ) modified experimental groups maintained stable carbon release during the later stages while keeping nitrogen and phosphorus levels low, which indicated their potential as promising candidate solid carbon-source materials for further evaluation for CWs. Aging also reduced the fluctuations in organic matter release compared to unaged corn straw, consistent with the prior depletion of readily releasable components during natural exposure. Chemical modification suppressed excessive initial organic carbon release and maintained a more controlled release profile during the later stages. The release behavior of COD and DOC was consistent. The research results promote the high-value utilization of biomass materials.